Worldwide, many millions of tons of plastics (or polymers) are generated annually for consumer use in households and commercial establishments. Much of such amounts of post-consumer plastic enters the municipal solid waste (MSW) stream with plastics representing upwards to 20% of an MSW landfill's volume.
The majority of post-consumer waste plastic originates from packaging and containers. This includes water and soft drink bottles and cosmetic containers, as well as disposable plates, cups and cutlery. Soft drink, water and dairy product containers are frequently produced from polyethylene terephthalate (PET). Water jugs, milk jugs and shampoo bottles are frequently fashioned from high density polyethylene (HDPE). Disposable cups, plates and cutlery are frequently made from polystyrene (PS).
Most residential recycling programs in the United States and elsewhere recycle only the polyethylene terephthalate (PET) and the high density polyethylene (HDPE) portions of their collected plastics. The plastics that are not recycled are landfilled. Overall, only a small fraction of all plastics produced are recycled.
One factor which influences this relatively low recycling rate is the potential need to separate recycled plastics by type. Products prepared from unseparated recycled mixtures comprising articles of a variety of incompatible plastic types can exhibit physical, structural or other properties and characteristics which are inferior to products made from their individual parent materials. However, the practical possibilities of completely sorting mixtures of potentially incompatible plastics into groups of like plastics are very limited from the technical and economic standpoints. Prior technology thus creates the problem of what to do with unseparated mixtures of post-consumer plastic articles.
Given the foregoing situation, it would be advantageous to develop processes for producing commercially useful products from mixtures of recycled post-consumer plastic articles without the need to completely separate such articles into different streams of articles of like plastic type. Such processes could create an incentive to recycle more of the available post-consumer plastic articles, thereby sending fewer of such post-consumer plastic articles to landfills. The invention described and claimed herein addresses this need for technology for converting unseparated, i.e., at least not completely separated, mixtures of different types of post-consumer plastic articles into commercially useful structures. The invention herein thus provides a solution to the problem of how to commercially utilize unseparated mixtures of post-consumer plastic articles.